Alarm clock



May 24, 1938. H. JUNGHANS ALARM CLOCK Filed July 16, 1935 l nt/e72. Z OF I HeZ H/Z rfuwgfiarzs X WWAZ Z W Patented May 24, 1938 UNITED STATES PATENT OFFICE ALARM CLOCK Application July 16, 1935, Serial No. 31,705 In Germany August 11, 1934 2 Claims.

This invention relates to controls for alarm clocks in which the alarm can be stopped before ringing commences.

In the case of a known arrangement, the stopping is effected by a hook connection resistant to tensile strain being established between a manipulatable stop lever in its alarm stopping position, and the winding stem of the alarm, this connection being such that it is released upon subsequent re-winding. The stop lever is held in operative position by means comprising a spring secured to the said lever and adapted to become engaged with a tooth in a gear acting as a ratchet wheel on the alarm stem, which spring is automatically lifted out of engagement with the gear when the alarm spring is r'e-wound. The foregoing is illustrated for example in German Patent No. 607,851.

The present invention provides an improvement in this construction as regards production and reliability of action. Instead of the gear on the winding stem, which is diflicult to produce and is not sufiiciently reliable owing to its small diameter and shallow teeth, the present invention provides a resilient detent dependent on the movement of the winding stem, with which detent the end of the stop lever may engage. The possibility of locking the alarm before the release of the alarm mechanism is due to the fact that the detent is frictionally operated directly from the winding stem, in such a manner that it is moved into the position for engaging the stop lever upon cessation of the turning of the stem.

The accompanying drawing shows a constructional example of the arrangement in elevation (Figure 1), side view (Figure 2) and plan (Figure 3). Figure 4 is a detail.

Fig. 5 is a perspective view of the detent and its arm. Fig. 6 is a perspective view of the detent.

The alarm escapement wheel I causes the hammer 3, in the known manner, to swing to and fro through the medium of the alarm anchor 2 for the purpose of striking against the bell. When the stopping button 4 is depressed, the stop lever B pivoted on the rod 6a and normally held in its uppermost position by the spring 5, is pressed against a lever I of the hammer shaft 1' and thereby prevents this shaft and the alarm escapement wheel from moving.

In order to ensure this stopping position, the end of the lever 6 becomes engage-d under a resilient detent 9, which is secured to an arm 9. This arm 9 is loosely mounted about the winding stem l0 and is carried along by the movements of the winding stem through friction set up by a spring H, to the extent permitted by its upper fork-shaped part, the movement of which is limited by a pillar l2. In the state of rest, the detent arm 8, 9 is always in the position shown by the full line in Figure 1, as the running down 5 of the winding stem during the ringing takes place in the clockwise direction. In this way the detent 8 is always ready to hold fast the depressed lever 6. When the arm 9 is in its normal position of rest and the button 4 is depressed, the stop lever 6 causes the detent 8 to flex backwards and then engages beneath the latter. The arrangement is such that the detent 8 will flex without causing the arm 9 to be turned from its rest position, the arm 9 being held frictionally with sufficient firmness to prevent such flexing from having any such effect. Upon winding up, which takes place by rotation of the winding stem ill in a counterclockwise direction, the detent arm 9, 8 is turned by friction into the posi- 20 tion shown by the dot and dash line, whereby the lever 6 is again released and snaps upwards owing to the action of its spring 5. The mech anism is thereby again released for further ringing. At the end of the winding up operation when the winding key is no longer turned in the counterclockwise direction, but is released, the usual ratchet and pawl arrangement associated with the alarm spring comes into action to check backward movement of the winding stem ID. This ratchet I4 and pawl [5 will, however, allow a slight clockwise movement of the winding stem, owing to the fact that the teeth of the ratchet wheel are rather coarse; at the most, this clockwise movement will correspond to the full width(s) of the teeth of the ratchet wheel. Nevertheless, such slight clockwise movement is made sufflcient to cause the arm 9 to be moved from its position shown in Fig. 1 in chain dotted lines to that shown in full lines. Thus, after the winding operation is completed, the arm 9 and detent 9 are again returned to their position of rest, in which they may once more coact with the stop lever B. In case the winding up operation ceases just after the holding pawl has passed a ratchet tooth, a sufficient backward movement of the winding stem will still occur due to the fact that the teeth are undercut and also due to the fact that there is some backlash in the gear train.

Assuming the stop lever 6 is depressed and is being held in the dotted line position of Figure 1, then due to the winding of the spring and resultant initial motion of the member 9 in a counterclockwise direction, the detent will be released to place the alarm in operable position,

(namely, where it is held from operation only by the timing mechanism). Also as soon as the winding operation ceases the detent member 8 and 9 has a slight clockwise rotation due to reaction of the spring which brings the detent into position Where upon depression of the member 6 the detent will hold the same so as to hold the alarm silenced.

The return movement of the detent 8 to full line position at the end of the winding operation is possible only when the space or play between one side of the shaft l2 and the adjacent inner side of one of the legs of the U-shaped part 9 is less than the pitch of a tooth on the winding ratchet.

I claim:

1. Alarm control for clocks, comprising alarm sounding means, a lever movable into and out of position for stopping movement of the sounding means, an alarm winding stem, a flexible detent capable of retaining the stop lever in operative position, and an arm carrying the detent, said arm being frictionally rotatable by the stem When it is turned in alarm winding direction to cause the detent to release the stop lever and to restore the detent on said arm into position for engaging the stop lever when the stem has ceased turning and it turns slightly in alarm unwinding direction after the Winding stem is released.

2. Alarm control for clocks, comprising alarm sounding means, a lever movable into and out of position for stopping movement of the sounding means, an alarm winding stern, a flexible detent capable of retaining the stop lever in operative position, an arm carrying the detent, said arm being frictionally rotatable by the stem when it is turned in alarm Winding direction to cause the detent to release the stop lever and to restore the detent on said arm into position for engaging the stop lever when the stem has ceased turning and it turns slightly in alarm unwinding direction after the winding stem is released, and means for limiting the arc of rotation of the arm.

HELMUT J UNGHANS. 

